1. Field of the Invention
The present invention relates to a key telephone system (hereinafter often referred to simply as "KTS"), a maintenance method therefor, and a medium on which is recorded a program for executing the maintenance method. More particularly, the present invention relates to a key telephone system which immediately and flexibly performs, at low cost and through remote control, a change in the main program of the key telephone system, recovery from failures, and maintenance operations such as diagnosis; to a maintenance method for the key telephone system; and to a medium for recording a program for executing the maintenance method.
2. Description of the Related Art
Like a private branch exchange (PBX), various key telephone systems have already been proposed as a system for providing business users with telephone exchange service. The PBX originated as an exchange for connecting private telephone lines, and during the course of its development a function of connecting the private telephone lines to a telephone network has been added to the PBX. In contrast, the key telephone system originated from the idea of making convenient connection to the telephone network through use of a plurality of telephone sets; for example, through switching of branch telephones. The function of inter-communication between extensions was later added to the key telephone system. In recent years, there has been no definite distinction between the PBX and the KTS, and a choice between the PBX and the KTS is a mere matter of the user's preference.
FIG. 8 shows the configuration of a telephone network system using such key telephone systems. A conventional key telephone system 101 has two built-in CPU cards 111, 112, in that the CPU card 111 is used as a main CPU card and the CPU card 112 is used as a standby CPU card. The KTS 101 further comprises a built-in analog/digital extension card 113 to be used as an extension interface card and a built-in analog/digital outside line card 114 to be used as an outside line interface card. These four cards 111 to 114 are connected together by way of a system bus and a system PCM highway 115.
The KTS 101 is connected to an analog/digital network 103 by way of the analog/digital outside line card 114 and is further connected to a maintenance site 102 by way of the analog/digital network 103. The maintenance site 102 is made up of a MODEM/TA (modem or a terminal adapter) 51 and a PC (personal computer) 52 and performs maintenance remotely.
The maintenance of such a conventional KTS 101 will now be described. The main program of the KTS 101 is changed on-site through operations such as exchange of memory, or a CPU card, of the KTS 101. Recovery of the KTS 101 from failures is performed by remotely switching the CPU card 111 to the standby CPU card 112. Further, the KTS 101 is diagnosed by means of operations performed through a digital telephone set or personal computer disposed at the client's location. To remotely diagnose the KTS 101, a diagnostic program incorporated into the KTS 101 beforehand is activated, and the result of such diagnosis is remotely transmitted to equipment installed at a remote site.
As mentioned above, with regard to the conventional key telephone system and the maintenance method therefor, and the medium for recording the program for executing the maintenance program, remotely changing the main program of the key telephone system requires two CPU cards, i.e., the main CPU card and the standby CPU card, thereby increasing the cost of the key telephone system. Further, providing two CPU cards to a key telephone system which usually operates through use of a single CPU card is wasteful even in terms of system configuration.
To remotely diagnose the key telephone system, one type of diagnostic program previously incorporated into the key telephone system is activated irrespective of system configuration. Accordingly, flexible and immediate activation of a relevant diagnostic program corresponding to the installation conditions of the key telephone system or to the nature of failure has been impossible. Further, if maintenance personal desires to change the built-in diagnostic program of the key telephone system, the CPU cards of the key telephone systems disposed at the client's location must be exchanged, thereby requiring an enormous amount of time and money.